This project seeks to measure psychophysiological differences that have been reported to exist across the alter personality states of patients with multiple personality disorder (MPD). Alter personalities of MPD patients are studied on a range of measures including: spontaneous EEG, auditory and visual evoked potentials, cerebral blood flow, continuous catheter venous sampling, psychological tests and measures of autonomic nervous system activity such as galvanic skin response, skin temperature, pulse and respiration. Simulating normal control subjects serve as a comparison group.